<?php
function imageWaterMark($groundImage,$waterPos=0,$waterImage="",$waterText="",$fontSize=12,$textColor="#CCCCCC", $fontfile='arial.ttf',$xOffset=0,$yOffset=0){
   $isWaterImage = FALSE;
     //读取水印文件
     if(!empty($waterImage) && file_exists($waterImage)) {
         $isWaterImage = TRUE;
         $water_info = getimagesize($waterImage);
         $water_w     = $water_info[0];//取得水印图片的宽
         $water_h     = $water_info[1];//取得水印图片的高

         switch($water_info[2])   {    //取得水印图片的格式 
             case 1:$water_im = imagecreatefromgif($waterImage);break;
             case 2:$water_im = imagecreatefromjpeg($waterImage);break;
             case 3:$water_im = imagecreatefrompng($waterImage);break;
             default:return 1;
         }
     }

     //读取背景图片
     if(!empty($groundImage) && file_exists($groundImage)) {
         $ground_info = getimagesize($groundImage);
         $ground_w     = $ground_info[0];//取得背景图片的宽
         $ground_h     = $ground_info[1];//取得背景图片的高

         switch($ground_info[2]) {    //取得背景图片的格式 
             case 1:$ground_im = imagecreatefromgif($groundImage);break;
             case 2:$ground_im = imagecreatefromjpeg($groundImage);break;
             case 3:$ground_im = imagecreatefrompng($groundImage);break;
             default:return 1;
         }
     } else {
         return 2;
     }

     //水印位置
     if($isWaterImage) { //图片水印 
         $w = $water_w;
         $h = $water_h;
         $label = "图片的";
         } else { 
     //文字水印
        if(!file_exists($fontfile))return 4;
         $temp = imagettfbbox($fontSize,0,$fontfile,$waterText);//取得使用 TrueType 字体的文本的范围
         $w = $temp[2] - $temp[6];
         $h = $temp[3] - $temp[7];
         unset($temp);
     }
     if( ($ground_w < $w) || ($ground_h < $h) ) {
         return 3;
     }
     switch($waterPos) {
         case 0://随机
             $posX = rand(0,($ground_w - $w));
             $posY = rand(0,($ground_h - $h));
             break;
         case 1://1为顶端居左
             $posX = 0;
             $posY = 0;
             break;
         case 2://2为顶端居中
             $posX = ($ground_w - $w) / 2;
             $posY = 0;
             break;
         case 3://3为顶端居右
             $posX = $ground_w - $w;
             $posY = 0;
             break;
         case 4://4为中部居左
             $posX = 0;
             $posY = ($ground_h - $h) / 2;
             break;
         case 5://5为中部居中
             $posX = ($ground_w - $w) / 2;
             $posY = ($ground_h - $h) / 2;
             break;
         case 6://6为中部居右
             $posX = $ground_w - $w;
             $posY = ($ground_h - $h) / 2;
             break;
         case 7://7为底端居左
             $posX = 0;
             $posY = $ground_h - $h;
             break;
         case 8://8为底端居中
             $posX = ($ground_w - $w) / 2;
             $posY = $ground_h - $h;
             break;
         case 9://9为底端居右
             $posX = $ground_w - $w;
             $posY = $ground_h - $h;
             break;
         default://随机
             $posX = rand(0,($ground_w - $w));
             $posY = rand(0,($ground_h - $h));
             break;    
     }

     //设定图像的混色模式
     imagealphablending($ground_im, true);

     if($isWaterImage) { //图片水印
         imagecopy($ground_im, $water_im, $posX + $xOffset, $posY + $yOffset, 0, 0, $water_w,$water_h);//拷贝水印到目标文件        
     } else {//文字水印
         if( !empty($textColor) && (strlen($textColor)==7) ) {
             $R = hexdec(substr($textColor,1,2));
             $G = hexdec(substr($textColor,3,2));
             $B = hexdec(substr($textColor,5));
         } else {
           return 5;
         }
         imagettftext ( $ground_im, $fontSize, 0, $posX + $xOffset, $posY + $h + $yOffset, imagecolorallocate($ground_im, $R, $G, $B), $fontfile, $waterText);
     }

     //生成水印后的图片
     @unlink($groundImage);
     switch($ground_info[2]) {//取得背景图片的格式
         case 1:imagegif($ground_im,$groundImage);break;
         case 2:imagejpeg($ground_im,$groundImage);break;
         case 3:imagepng($ground_im,$groundImage);break;
         default: return 6;
     }

     //释放内存
     if(isset($water_info)) unset($water_info);
     if(isset($water_im)) imagedestroy($water_im);
     unset($ground_info);
     imagedestroy($ground_im);
     //
     return 0;
}
?>